1. Field of the Invention
The invention relates to oxygen enriched air. More particularly, it relates to the production of oxygen enriched air by the use of a pressure swing adsorption and a related air blending control system.
2. Description of the Prior Art
There are numerous industrial applications in which oxygen enriched air is desirable for enhanced combustion purposes. In such applications, liquid oxygen is commonly shipped to an on-site liquid storage tank for blending with air to produce the desired purity level of oxygen enriched air. The liquid oxygen used for this purpose typically has an oxygen concentration of 99.5+%. If the requirements for oxygen enriched air at the job site are sufficient to warrant, a cryogenic air separation unit might be installed at the job site to reduce the overall costs associated with the production and supply of oxygen enriched air for such industrial applications.
An alternative for some applications involves the use of permeable membranes suitable for convenient air separation operations. Such membranes generally separate air into a high purity, non-permeate nitrogen stream and an oxygen enriched, permeate stream. Membrane systems are simple and generally only produce oxygen enriched air in the 30-40% purity range, without the necessity for air blending. For certain relatively low volume applications, the use of on site permeable membrane systems may be used to supply oxygen enriched air. Pressure swing adsorption (PSA) systems have also been utilized to produce oxygen enriched air.
A significant field of practical commercial operation remains, however, in which the shipment of liquid oxygen from a centrally located cryogenic air separation plant to a storage facility on site, for subsequent air blending, remains the most economical means for supplying the needs for oxygen enriched air at an industrial facility. Nevertheless, the overall costs associated with such production of oxygen enriched air from liquid oxygen are relatively high, significantly affecting the feasibility of employing oxygen enriched air to enhance the efficiency of combustion furnaces and to achieve power savings in the operation of such furnaces. It will also be appreciated that different combustion furnaces will require different purities of oxygen enriched air for most efficient operation. It is a desire in the art, therefore, that improvements be made in the production of oxygen enriched air for such combustion operations, particularly improvements enabling oxygen enriched air at desired purity levels to be produced and supplied at lower costs than is presently possible by the blending of liquid oxygen with air.
It is an object of the invention, therefore, to provide an improved system for the production of oxygen enriched air.
It is another object of the invention to provide an improved system for the on site production of oxygen enriched air not based on the shipment of liquid oxygen to the plant site.
With these and other objects in mind, the invention is hereinafter described in detail, the novel features thereof being particularly pointed out in the appended claims.